Concrete pump



Oct. 22', 1935. J. c. KOOYMAN CONCRETE PUMP 4 Sheets-Sheet l Fiied Jan.16, 1955 Jacobus Cli'ooyman,

Oct. 22, 1935. J. c. KOOYMAN CONCRETE PUMP Filed Jan. 16, 1953 4Sheets-Sheet 2 lll lllflllllllll llll Ill/Ill IIIIIIIIIIIII/ 4Sheets-Sheet 3 J. C. KOOYMAN CONCRETE PUMP Filed Jan. 16, 1933 JCZCOELLSafi ao ylnan,

arty/"Maw Oct. 22 1935. J. c. KOOYMAN CONCRETE PUMP Filed Jan. 16, 19334 Shets-Sheet 4 r Q 0 W W Rm m a Q m A a I HHH| J Q Q a Patented on. 22,1935 UNITED STATES PATEN/T OFFICE Application January 16, 1933, SerialNo. 652,077 In the Netherlands February 17, 1932 24 Claims.

The present invention relates to pumps for handling concrete and otherplastic mixtures similar to concrete in respect to certain physicalcharacteristics hereinafter referred to, and has for one of its objectsto provide an improved pump for such service which will effectively pumpnot only wet, free-flowing mixtures containing relatively lowpercentages of coarse aggregate of small or medium size, but alsoconcrete mixtures 1Q incorporating a high percentage of coarseaggregate, frequently of large size, as well as mixtures of a semi-drynature, which by reason of their relative dryness are extremelydiflicult to pump. Another object is to provide a pump of 13 this naturewhich is characterized by such durability, such avoidance of mechanicaltroubles heretofore encountered in handling these trouble-breedingmixtures, such accommodation of normal wear, and such ease ofmaintenance and 20, reduction in cost thereof, that it will in practiceout-perform any previous concrete pump of which I am aware. In short, mygeneral object is to provide pumping means by which concrete, includingsmall-slump mixes having a very high 25 percentage of coarse aggregatewhich may be of the maximum sizes demanded by widespread present daycommercial practice, may be pumped with greater economy andeffectiveness, and with less deterioration of the pump, and less trouble30 in its operation and/or upkeep, than has heretofore been possible.

Concrete, as defined by the American Concrete Institute, is a mixture inwhich a paste of Portland cement and water binds fine and coarse ma- 35.terials, known as aggregates into a rock-like mass as the paste hardensthrough the chemical action of the cement and the water. This definitionis somewhat more limited than the com-' monly accepted understanding ofthe word, 4 which is widely used to designate mixtures in which the fineand/or coarse aggregates are held together by binders other than acement-andwater paste, such for example, as the well known asphalticconcretes. The term concrete is also 45 loosely applied, particularly bylaymen, to mixtures of fine aggregate and cement-and-water paste,although technically such mixtures are more properly termed mortar orgrou In the present specification and claims, the word 50 concrete isintended tomean a conglomerate mixture of fine and coarse aggregateswith a binder, but excluding the fine-aggregate-andbinder mortars orgrouts; and the apparatus and method will be set forth principally withrelation to Portland cement concrete, although not strictly limitedthereto.

The aggregates "above referred to are inert materials, which play nopart in the chemical reactions between the water and cement which re- 60suit in the hardening or setting" of the mixture,

and are employed principally to increase the mass and reduce the cost ofthe product. The larger or "coarser the largest aggregates used, thecheaper is the concrete, generally speaking.

The most commonly used form of fine aggregate is sand, while gravel andcrushed rock are the most common forms of coarse aggregate. The size ofthe gravel or crushed rock used in concrete is commonly stated in termsof the size of the openings in the size-grading screen through which thematerial has passed. Any aggregate up to inch size is considered fine,while coarse aggregates in present commercial use may range from inchsize up to 2 or 3 inches, or even more. Aggregates ranging about 2inches or above I will refer to as very coarse for convenience.

Because of its initial plastic nature, hydraulic cement concrete isusually, although not always, introduced into forms of suitable shape,acquir- 2 ing their configuration, and retaining it after setting.Originally, the placement of plastic mixtures was a hand operation,accomplished with the aid of shovels, wheelbarrows, and wheeled carts orconcrete buggies. This method of placement is in use today to a largeextent on small structures, but with the advent of plasticmixtures inthe building of structures of large magnitude, either in length, area,or height, the socalled tower method of placement has come into ratherwide use. This method involves the erecting of one or more skeletontowers which serve as an elevator framework, in which elevator cars,usually in the form of receptacles for the concrete mixture, are raisedand lowered by means of a cable and winding drum. Near the top of thetower, the upper end of an inclined. chute is secured, the lower end ofwhich is positioned above the form which is to receive the mixture. Theconcrete is elevated in the tower to receptacle and dumped into theupper end of the chute, down which it flows by gravitational action intothe form.

A modified tower method has also gained rather wide use in which thechute is dispensed with. The concrete is hoisted in the usual inanner inthe tower and discharged from the tower car into hoppers or receivingreceptacles from where it is drawnpfi into concrete buggies and wheeledmanually to the forms to be filled with the mixture. The several towermethods and apparatus, while in rather extensive use, are objectionablefrom the standpoint of the cost of the tower structure, and its erectionand .dismantling on each job; also, when using the distributing chute,because of the tendency of the larger and heavier aggregate of theconcrete mixture, if it be wet enough to flow in the chute under theaction of gravity, to segregate from the smaller and lighterconstituents, so that the two are deposited In special cases, requiringthe placing of a great quantity of concrete, as in a dam, or in anextensive area,-as in buildings andindustrial plants, belt conveyors,motor trucks, and small narrow gauge railroad cars have been used totransport concrete to the forms.

It has also been proposed to force concrete and mortar mixtures throughpipes, both by pneumatic and by mechanical pressure. The pneumaticmethod has proven too costlyfor use except in very diiiicult placements,such as the arch portion of concrete lining for tunnels; the majorportion of the concrete in the tunnel lining being placed by othermeans, and only the top portion of the arch of the lining being placedpneumatically. The fact that pneumatic power is mechanically veryinefllcient and too costly for use to any great extent, is well known.

Beside the mechanical inefficiency of pneumatic pressuremeans of placingconcrete, there are other draw-backs to this method; e. g. the concretein many cases is apt to be so wet as to separate in the pipe, with theresult that the gaseous pressure blows the lighter constituents (thewater, sand and cement) through faster than the coarse aggregates.

The pneumatic systems generally discharge only intermittently, aspneumatic pressure must be built up back of the concrete before it canbe forced through the pipe. The usual practice is to charge a batch ofconcrete into the charging tank of the system, which is then tightlyclosed and the concrete is blown through the pipe, after which the flowof air is stopped, the tank is opened to receive the next batch ofconcrete, and the operation is repeated. The discharge of concrete fromthe end of the pipe is diflicult to control. stoppage of the pipefrequentb' occurs, excessive pressure is built up within the system, andif it finally overcomes the resistance, the material is shot out in awholly uncontrollable manner.

It has furthermore been proposed to force grout mixtures and evenconcrete in which the coarsest aggregates are quite small, though pipesby means of centrifugal pumps, but up tothe present, no commerciallypractical way of accomplishing this has been devised to the best of myknowledge.

On the other hand, there has been developed in Europe, within the lastfew years, a pressure pump of the reciprocating piston type which has,within a limited range of wet" oversanded" mixes wherein no very coarseaggregates were used, successfully handled concrete, discharging thesame in a substantially continuous but pulsating stream. Because oflimitations on the possible field of use imposed by ture of such mixes,and because of troubles arising from the pumping method, this practicenever became extensive.

These pumps last referred to employed ball check valves, working invalve chambers of much greater size than the balls, which latter weredesigned to seat tightly during proper portions of each cycle of thepiston to prevent back costly na-.

flow. These valves, however, were a never-ending source of troublebecause of the inherent character of concrete; and while the pumps, asabove stated, were successful in a measure in handling wet over-sandedmixes, where the 5 coarse aggregates with rare exceptions did not exceed1% to 1% inches in size, and constituted a relatively small percentageof the mixture, under which circumstances they could be considered asfloating" in the sand and cement 10 paste mixture, they were incapableof handling such mixtures as are most commonly used wherein the coarseaggregate normally exceeds 50% of the constituents of the mix andfrequently contains pieces 2 or 3 inches, or even 15 more, in size.

There are several reasons why pumps using ball check valves are severelylimited as to the mixes which they are capable of pumping. With the balltype valve-and the same is true of go flap valves, mushroom valves, andother types in which the flow of material opens the valve and reverseflow, or gravity, tends to close it-it is necessary to allow suiilclentclearance between the movable valve member and the valve hous- :5 ingwhen open, to permit the largest sized materials to pass. For example,the above mentioned pumps are provided with mm. (3.54 in.)

passages or ports, and mm. (4.33 in.) balls controlling them, while thevalve chambers, a which are tapered, range from 235 mm. (9.20 in) to 285mm. (11.25 in.) in diameter. As a result the net area of the valvechamber is so much greater than that of the port that the concrete tendsto channel; i. e., it takes the path of a, least resistance around theobstructing valve member, while the mix in the annulus outside of thiszone becomes dormant, hardens, and builds up until the ball can nolonger move back and forth to perform its function. This condiw tion isalso aggravated by the presence of the guides necessary to center theball valve.

A normal concrete mixture, which has a large percentage of solidpiecesof irregular shape, even in the so-called wet mixes" .does notfollow the 45 well recognized law of fluids. For example, a liquid orgas flowing through a closed pipe or conduit at a given rate, uponencountering a-re-v striction in such conduit, will increase itsvelocity at that point in passing the obstruction, 50 whereas a normalconcrete mixture, upon encountering a sudden restriction, while passingthrough a closed conduit, will reduce its velocity and tend to pack orstow at such point so as to completely stop the flow.

In valves of the above mentioned type, the movable valve members and theguidestherefor, are of necessity positioned in the line of flow andconstitute obstructions about which the mixture must be forced. Inconsequence, the passages go through which the concrete is forced mustbe of acomparatively irregular, locally restricted, and tortuous nature,so much so that the normal mixes (having a high percentage of coarseaggregate, frequently of large size and/or of a semi-dry 5 nature) tendto pack or stow in these passages. This "stowing may suddenly occur inany part of the passages and when it once takes place, the pump soonbecomes wholly inoperative.

Advantage has been recently taken of this prop- 1o erty of concretemixtures, with respect to the construction and operation of the valvesof concrete pumps, whereby the range of large-aggregate mixtures capableof being handled by such pumps, and their reliable efliciency, has beenvery materially increased over thosebefore proposed. That is to say, aconcrete pump has been developed in which the valves are so constructedand arranged as to present, in their open positions, free andunobstructed passageways for the mixture, and these valves are purposelyonly'partially closed, in their proper sequence and relation to theworkings of the piston or other pressure member, so as only to partiallyrestrict and never to completely out off said passageways. The mixturestows at such restrictions and completely prevents back flow, and thenecessity for completely-closing, accurately seated valves is obviated,with the consequent elimination of most of the valve trouble previouslyexperienced.

Such a pump is described and claimed in the co-pending application ofOtto Kastner, filed January 16, 1933, Serial No. 652,081, entitled"Method of and apparatus for pumping concrete and forms of valvescapable of successfully carrying out the above principle are shown anddescribed. One form comprises sliding gates or dampers which arealternately moved transversely of the passageways from positions whollyclearing said passages to positions partially but never completelyclosing them, and back again. In another form, the passageways areprovided with flexible or resilient sections, normally of the samediameter as the passageways, which may be partially collapsed andrestricted by pressure exerted on their exterior by one or more movablejaws or levers, to serve as a valving restriction.

While such valve structures, as above stated, are quite capable ofsuccessful operation, actual experience has shown that the firstmentioned form requires a relatively large amount of power, particularlyin the closing movements, and in the case of the second mentioned form,the resilient conduit sections are subject to comparatively rapid wear,necessitating frequent replacements, which of course means that themachine must be shut down.

It is one of the principal objects of the present invention to improvethe valve structure and operation of concrete pumps of the type referredto above, and I have found from actual experience in building andoperating these pumps that,

contrary to the opinions heretofore held by recognized concrete pumpengineers, oscillating plug valves may be successfully and efflcientlyemployed in such pumps with excellent results if the plug be axiallysupported at its ends, and the valve be made seatless; that is, withoutprovision for any close fit (or approximation there: of) between theported zone of the housing and the corresponding zone of the movablemember;

provision being made, instead, for complete circumferential clearancebetween the plug and housing, in at least the zone of their ports,-which is ample in depth or radial dimension freely to accommodate inflowand outflow therethrough of what I will term the "paste-flowableconstituents of the mixture; that is to say, the fluid paste of waterand cement together with such small solid particles of the aggregate(being chiefly the finer sand grains) as float in the paste or aretenaciously carried by it and are therefore almost inseparable from itsflow and that such employment gives marked conservation of power andgreatly increased length of life. Such valves may be made withreplaceable parts so that when unduly worn, due tothe abrasive action ofthe cement and fine aggregates, they may be replaced with new parts;however, due to the fact that complete closure of the passages is notnecof an oscillating plug, with a passage through it, 5

provides two spaced solid or passage-restricting elements, which whenthe valve is turned to restricting position, constitute a doublerestriction within the passage, thus practically doubling the efliciencyof the valve, and greatly proionginl its 1 efiective life.

I have found it to be highly important, for

capability of the apparatus to handlerand its emciency in handling,commercial mixtures and particularly those characterized by small-slump5 and/or'large percentage of very coarse aggregate, to have the outletand inlet passages (including the passageways through the outlet andinlet valves) of the same cross-sectional shape and nearly the samecross-sectional area as the 20 pump cylinder, so that the passage wallsneither aiford dead pockets in which the concrete may lag and harden,nor' abrupt restrictions compelling rearrangement of the coarseaggregates and in which the concrete may stow; and also to as have theoutlet passage axially alined with the pump cylinder, to receive eachpump-ejected mass of concrete from the cylinder with substantiallyminimum change of relative positions of the pieces of the coarseraggregates; while the so inlet passage is desirably so arranged relativeto the cylinder that the sectional shape which its walls give to theconcrete about to enter the cylinder also tends to minimize thenecessity for the coarser aggregates to rearrange themselves on 35entering the cylinder. For like reasons permanent restrictions orenlargements and also abrupt changes of cross-sectional shape and areaof the distribution piping should be avoided, after-the concrete leavesthe outlet valve.

Further, it is very advantageous in the operation of the pump that thecylindrical working chamber, the walls of'which are solid throughout theentire range of piston travel, shall provide a single axial end-openingthat is of full 4,5 cylinder-diameter and through which the concrete isboth received on the intake stroke of the piston and elected on thepistons discharge stroke and to have the walls of the valved inlet andoutlet passages, both of which open to the cylinders end-opening, struckon radii of approximately the same length as the radius of the cylinder,such walls merging at a point very close to the cylinders end-opening;this branched I structure being conducive to best handling of themixture into and out of the working chamber of the pump, good life ofthe pump-parts, and pumping efllciency.

In substantial effect the closing action of my valve may be described asthat of quickly displacco ing that section of a column of concrete whichI re-constituting a straight column. In my pump the fixed passages abovementioned and as well the orifice through the valve, are so shaped that,when the valve is open, the column of concrete walled about by them isof uniform cross-section 7Q valve-carried section of the column (whichis done in timed relation to the piston travel, of course)' back-flow ofthe concrete is prevented. This is done chiefly by the portions of thevalve which close off portions of the ends of the contiguous fixedpassages, but is dependent also on the stowing of the concrete at therestricted openings which are left,-due to the valve never completelyclosing. Of course it cannot be said, in the most rigorous meaning ofthe words, that the valve-contained section is bodily displaced fromalignment with the-passage-contained part of the column and bodilyrestored intact, since the valve action is not absolutely instantaneousnor is stowing, to completely stop the flow, absolutely instantaneous.In substantial effect, however, no such continuation of concrete flowoccurs during valve closure or through the intentionally-left partialopening of the valve aperture as will prevent re-formation of theconcrete into a continuous and uniform column promptly upon restorationof the valve to open position.

' In short, this utilization of a plug" type of valve,

with its orifice of equal diameter with the passages it controls, andthe rapid actuation thereoi-but actuation that intentionally leaves apartial through-opening to be closed by stowing of the concrete,is onethat is peculiarly eflective for taking advantage of the characteristicsof the concrete and for handling this diflicult material with greatestfacility.

For moving the valves to open and restricting positions, I prefer toemploy double acting cams, so shaped and positioned on the crank shaftof the pump as to provide in timed relation to the piston travel, theproper dwell or timeinterval during which the valves remain motionlessin their respective open and restricting positions to permit thesubstantially complete filling or emptying, as the case may be, of thepump cylinder, after which the said cams quickly and positively move therespective valves from open position to restricting position, and viceversa, as the piston travels away from the end of the cylin der. Thesemovements are accomplished by the engagement of the cams with one of twodiametrically opposed rollers positioned within a housing which isformed on the cam rocker arm.

It has been my experience that because'of the heavy nature andcomposition of concrete (largely composed of solid particles of varioussizes) it is important that the valves be positively and quickly openedand the use of springs to actuate the valves has been found to beunsatisfactory. Should a spring break, or lose its force to such extentas to fail to open the outlet valve, for instance, great damage might bedone to the machine on the pressure'stroke of the piston, due to theinability of the cylinder contents to escape; or should an inlet valvefail to open, the supply of mixture to the cylinder would fail and thepumping action cease.

It is equally important that the valves be actuated to restrict thepassages quickly and positively so as to prevent reverse flow of themixture and loss of pump efiiciency. However because of the highprecentage of coarse aggregates in the concrete,and frequent pieces oflarge pleted by the cam. I therefore provide a resilient 2,017,975throughout its length. In displacing the stated means in the rodconnecting the valve arm to the cam rocker arm so that when a piece ofaggregate is thus caught, the connecting rod will extend and permit thecam to complete its travel;

otherwise, withoutlthe resilient means, serious 5 damage or breakage tothe mechanism might take place.

As in the Kastner pump, provision is made for adjustment of the amountof restriction imposed by each valve, which in commercial practice isthe minimum restriction consistent with the stowing characteristics ofthe concrete being pumped. An adjustment leaving a normal openingapproximately the average size of the largest aggregate in the mixtureworks well with the 15 commonly used mixes,,e. g. mixes which areproportioned one part by volume of cement, two parts of sand, and fourparts of well graded gravel, with sufficient water to give a slump offrom 125 to 175 mm. in 300 mm., (approximately 5 to 7 inches in 12')although mixes having a greater tendency to stow than the mixes abovementioned may be accommodated by providing for lessrestriction by thevalve, and conversely, mixes with a lesser tendency-to stow may requirea somewhat greater restriction by the valve. In order to facilitatethese valve adjustments, an indicator is associated with each valve toshow its position and amount of restriction.

I have discovered that with my mechanically operated concrete pumpvalves it is not desirable to use an air dome or other pressureequalizing means on the discharge side of the pump, as commonly usedwith piston pumps 'in fiuid or gas pumping systems. stroke the dischargevalve is actuated to partially restrict, but never completely out ofl,the discharge passage, and before the piston has traveled a greatdistance on the suction stroke, the inlet valve is moved to release therestriction 0 of the'inlet passage. While the actuation of the valves isas rapid as practicable, nevertheless there may be a period in theiractuation where there is overlapping of the movement of the valves; thatis to say, the discharge valve may not reach its ultimate stowingposition until after the'inlet valve has been partially moved from itsstowing position. At this period in the movement of the valves, an airdome on the discharge side of the pump would compel a portion of themixture to return through the discharge valve into the pump and pass theinlet valve into the supply hopper. This reverse move-' I ment, termedback slip, is undesirable as it may greatly decrease the pumps deliveryof concrete. Without the use of an air dome on the discharge side of thepump, I find that the inertia of the mixture at the end of the pressurestroke of the piston when pumping concrete horizontally or evenvertically, will go far toward minimizing "back-slip" during that periodof valve relationship aforementioned, and the provision of passages andpiping of the size and'relationships heretofore stated is conducive tothis helpful inertia effect.

One form of concrete pump constructed in accordance with the presentinvention, and embodying the above features and objects, is illustratedin the accompanying drawings, forming a part of this specification, inwhich like reference char- 7? acters designate like parts in all theviews, and in which: I

Figure 1 is a side elevational view of the apparatus.

Figure 2. is a central longitudinal sectional 7 At the end of thepressure 35 direction of the arrows, and with the valve plug shown inrestricting position;

Figure 5 is a top plan view of the right hand portion of the valve shownin Figure.4, illustrating the indicating arm and scale;

Figure 6 is a longitudinal sectional view of one.

of of the connecting rod assemblies employed between the valve arms andthe cam rocker-arms, and showing the longitudinal adjustment, andyielding connections associated therewith;

Figure 7 is an enlarged side elevational view of the outlet valve cams,and the rocker arm or lever and housing associated therewith;

Figure 8 is a vertical sectional view, partly in elevation, of the partsshown in Figure 7, taken approximately on the plane indicated by theline 8-4! of the said 'figure, looking in the direction of the arrows;and I Figure 9 is a horizontal sectional plan view, taken approximatelyon the plane indicated by the line 9-9 of Figure 7, looking down.

Referring more particularly to Figures 1 and 2 there is shown a pumpmounted upon a suitable base or framework l0, comprising a bed II whichmay take the form of a casting secured to the said base and whichsupports the cylinder l2 having a working chamber l3 in which is mountedthe piston l4. This said piston preferably comprises a head l5 providedwith packing washers l6 and a hollow skirt portion l'l within which isjournalled as by the pistonpin l8, one end'of the connecting rod IS. Theother end of the said connecting rod is'journalled upon crank pin 20carried by the crank throws 2| of the crank shaft 22 journalled insuitable bearings 23 provided upon the bed II, which crank shaft alsocarries gear 24 which meshes with the pinion 25rigidly carried by a jackshaft 26. A pulley or sprocket 21 is also mounted upon the jack shaft 25for 7 receiving power through a belt or chain 28 from the pulley orsprocket 29 carried by the power shaft 30 of an internal combustion orother motor (not shown) mounted within the housing 3!. A suitable clutch(not shown) is interposed between the pulley or sprocket 21 and the jackshaft 26 whereby the transmission of power from the motor to the pumpmay be controlled at will, such clutch being operable by means of aclutch lever or handle 32.. as shown in Figure 1.

The cylinder l2, which is here shown as being disposed in a horizontalposition, is provided with an outlet port to which is connected ahousing 36 of the outlet valve which in turn discharges into the pipe orconduit 31 through which the material maybe conducted to the point ofuse; the outlet passage 42 being here shown as axially aligning with,and of the same diameter as, the pump-cylinder l3.

The cylinder l2 is also provided with an intake passage 38 whichapproaches the cylinder from above at substantially right angles to theaxis thereof and which is preferably curved substantially as shown inFigure 2to gradually merge therewith; the inlet passage being here shownas of the same diameter as the pump cylinder. The

The inlet and outlet valves are best shown in- Figures 1, 2, 3 and 4,and asthey are in all respects duplicates of one another, the outletvalve will be described in detail withthe corresponding parts oftheinlet valve indicated. by corresponding primed reference characters.As is best shown in Figures 2, 3 and 4 said outlet valve comprises thehousing 36 which may take the form of a casting having the longitudinalpassage '42 therein and provided with transverse bore 43 in which ispreferably mounted the tubular liner 44 having diametrically opposedports 45 in communication with said passage 42. The valve housing isprovided with removable end plates 46 and 41, see Figure 4', havingbearing bushings 48 and 49 respectively, to serve as journals for thestud shafts 50 and'5l which project from opposite ends of the valve plugmember 52. The said plug member 52 is provided with anon-storageinducing passageway 53 extending through it, which is adaptedto register with the ports 45 of liner 44 and passage 42 through thevalve housing when thevalve is in open position as shown in Figure 2.The passageway 53 through the plug member 52 produces a pair ofoppositely disposed solid portions 54, each of which serves to partiallyrestrict the pasageway through the valve housing when the plug member isturned to restricted position as indicated in broken lines in Fig. 2 andas is shown in Figure 4. There is thus provided the double restrictionof the passageway such as 42 above referred to, which increases theefficiency of the valve as well as its length of life, for should thesolid portion 54 which is nearer the piston in Figure 2 become wornthrough abrasion by the smaller aggregates after long continued use, theelement 54 which is farther from the piston and which has not beensubjected to so much wear would still serve to provide the necessaryrestriction of the pas, sage required to prevent reverse flow of themixture and thereby practically double the life of the valve plug.

As is clearly indicated in Figures 2 and 4, the

- the inner diameter of the liner 44 so as to provide in such zone acomplete circumferentialclearance 55 between the outer surface of theplug and the inner surface of the liner. This clearance is advantageousin the present case,

because of the fact that tight fitting and accurately seating valves, inoperation, are immediately scored or grooved by the fine particles ofcement and sand, regardless of how hard or wear resisting may be theplug and liner surfaces. Thereafter the cement-and-sand paste caught inthese grooves is drawnbetween the surface of the plug and liner to suchextent that the two are intimately bound together, so much so that itbecomes impossible to move the plug without breakage of some partthereof. Y

This clearance when the val e is new is preferably about fl; of an inchor slightly more, and considerable increase of the clearance, due to theslow abrasive wear, does not decrease the effectiveness'ofthe pump. Thewater and cement, to-

- 'to that indicated by the line A therein.

gether with portions of the sand or other fine aggregate, that findtheir way into this clearance have sufficient space to minimize scoringand wear, and the water-and-cement mixture carrying or coating the smallsolid particles of these paste-flowable constituents will serve as'asort of lubricant between the particles of fine aggregate and themetallic valve-surfaces, with results which seem in no wise detrimental,provided the paste is "not permitted to harden when the machine is notin operation. These constituents will of courseproduoe some abrasiveaction upon the surfaces, but since the clearance permits theconstituents to roll over on themselves, and the water-and-cement pasteto act as a lubricant, the Wear is relatively slow and is notdetrimental until the clearance approaches or reaches the maximum sizeof the fine aggregate, say A of an inch. In other words the valves maycontinue to ,function without appreciable loss of efficiency until theWearoccasioned by the abrasive action of the fine aggregates upon thecomplementary surfaces has increased the clearance to approximately A,,of an inch.

Clearance 56 is also provided between the ends of the valve plug 52 andthe end plates 46 and 41, as this also reduces friction and the powerrequired for the valve actuation. Resilient or yielding rings arepreferably provided encir- 1cling the end'portions of the valve plug 52which rings serve to a great extent to keep the sand or other abrasiveaggregate out of the end clearances 56 and thus out of the bearings 48and 49, although portions of the water and cement mixture willeventually find their way past these packings and into such clearances.However, as above explained the water and cement mixture alone is notparticularly detrimental unless permitted to harden, but on the otherhand, serves as a sort of lubricant between the adjacent surfaces. 'Inorder that these clearances maybe flushed out to prevent hardening, theend plates 46 and 41 are provided with apertures 58 normally closed byplugs 59 through which apertures -fiushing water or other medium may beintroduced and evacuated by means of detachable hose or conduits, notshown. I

The valve shaft 5| extends beyond the end plate 41, being provided witha suitable gland or stufiing box 60, and carries at its outer end anactuating arm 6| by means of which the shaft and plug 52 may beoscillated through mechanism to be hereinafter described. As best shownin Figures 3 and 4 this said arm may take the form -of a bifurcatedconstruction, each leg thereof be ing provided with an elongated slot62, .and the side walls of these slots are preferably serrated orprovided with recesses 63 for engagement by keys 64 carried by a pin 65which journals one end 'of the valve rod assembly 66. By positioning thepin 65 with its keys 54 in engagement with different recesses 63 in theslots 62 it is possible to vary the arcuate movement of the actuatingmember 6|, and consequently of the valve "plug 52 whereby the, degree ofrestriction imposed by the elements 54 of the valveplug may be varied.That is to say, as will hereinafter appear, the linear travel of thevalve rod assembly B6 always remains the same with the resultthat if thepin 65 be moved to the outermost end of the 'slots 62 as is illustratedin Figures 3 and 4, the arcuate travel of the actuating member 6| and ofthe plug 52 will be reduced to a minimum, say 45 or from the positionshown in Figure 3 On the shown may reach as high as 90.

event the pump was being used for handling grout i mixtures as abovedefined, and for ordinary purposes in the handling of concretemixturesembodying large aggregates, the arcuate travel of the plug52-should be less than 90? so that the maximum restriction produced byelements 54 15.'

will be only substantially as is illustrated in broken lines in Figure2. In other words the new ate travel of the arm 6| and plug 52 inpractical handling of concrete mixtures will range from between 45 tosay 75.

This variation in the travel of the valve plug and the consequent degreeof restriction of the passage 42 as above explained is desirable inorder that such restriction may be changed in accordance with theaverage maximum size of the large aggregates being handled. In otherwords, it is preferred to so set the valve that when it reaches itsrestricting position the opening still remaining between the points 10of the members 54 and points H of the liner 44 will be approximatelyequal to or slightly greater than the average size of the largestaggregate in the, mixture. It thus resultsthat if a piece of largeaggregate is present in the line of travel of the elements 54. as theymove to restricting position such ele- 85 ments will 'not be called uponto crush such piece of aggregate but will stop at a point short ofactual crushing engagement. On the other hand, should a piece ofaggregate greater than average size be present so that it would becaught between the edges 10 and II as the valve clo'ses, provision ismade in the valve rod assembly for absorbing the strain thus imposed andfor relieving the crushing action in order to pre-'. vent damage to thevalve and other portions of 4,5 the machine, all as will be morev fullyhereinafter described.

In setting the valves for aggregates of difl'erent sizes the fully openposition shown at the left of Figure 2 and indicated by the line A inFig-v l0 ure 3 is employed as the zero point and in order to quicklyshow this point, as well as the degree to which the valve may restrictthe passage 42, the end plate 41 of the valve housingis provided with asector 12 having a series of graduations sirable and it is thereforepreferred to employ 65,

cam action for moving the valves in both directions. One practical formof cam mechanism for actuating the valves is illustrated in Figures 1,7, 8 and 9 and will be described in detail with reference to themechanism for actuating the outlet valve, it being understood,'however,that substantially the same mechanism is employed for the operation ofthe inlet valve, the only difference being that the cams for the inletvalve are of slightly different shape,and are set at ap- 04 and 05,slotted as at 86 and 01 respectively to accommodate the end of the.crank shaft 22. The said side plates support studs 80 and 89respectively upon which are rotatably mounted rollers 90 and SI, as willbe clear from Figures 7 and 9.

The cam 80 is formed in two adjacent sections which may be machined froma single piece of material or each section may be separately formed andthe two rigidly connected together in any desired manner; The section 92of the cam is disposed in such position that it will be engaged by theperiphery of the roller 90 while the companion section 93 of the cam isarranged so that it will be engaged by the periphery of the roller 9|.,Assuming the parts to be in the positions shown in Figure '7 and thecrank shaft and cams rotating in the direction indicated by the arrows,the cam section 92 has through its engagement with the roller 90 movedthe rock lever 8| about its pivot 82 in a counter-clockwise directionand it is obvious that further rotation oi. the crank shaft and the cam80 will cause the section 93 thereof, through its engagement with rollerSI, to produce a positive reverse movement of the rock lever 8| to aposition such as that indicated by the broken lines in Figure 7. The camsections are so designed and con-- structed that the movement toward theright,

as'viewed in Figure 'l, imparted by cam section 03 will not take placeuntil the high portion of cam section 92 has cleared the roller 90, andvice versa, the return movement of the parts will not be accomplisheduntil roller 9| has been cleared from the high portion of cam section93. A positive oscillating movement in each direction is thus impartedto the rocker lever 0i in timed relationship to the movements of thecrankshaft 22, which movement is transmitted to the actuating arms suchas SI of the valve in order to produce the necessary oscillation thereofto move it from open to restricting position and back again.

The motions of the rock lever 0i 7 are transmitted to the valveactuating arms BI through connecting rod assemblies 00 such as are shownin detail in Figure 6. That is to say, a threaded rod 90 hasone of itsends such as tlpivotally connected as at 01 to the ears or lugs'll,carried by the upper portion of the rock lever 0|. A hollow sleeve 09provided with a reduced portion I00 threadedly engages the rod and alock nut IOI may be provided for securely lockone end of 'which isprovided with a head I01 having a bearing I0! adapted to receive the pin7; .00 which serves as a connection between the corinecting rod assembly66 and the valve actuating arm 6| as above set forth.

The other end of the tubular member I06 is provided with a flange orenlargement I09 against which abuts one end of a coil spring H0, 5

the other end of which abuts against a collar II I provided with asuitable thrust bearing II2 to take the end thrust.

In the movement of the connecting rod assembly from right to left, asviewed in Figures 1, 6- and 7, the force istransmitted from the threadedrod 95 to the sleeve member 90 threaded thereon and from it directlythrough the flange or enlargement I00 to the tubular member I06 andthence through the pin 65 to the valve actuating arm 6|, therebyproducing positive motion of thevalve from closed to open position. Inthe reverse movement of the parts the pull upon the rod 95 istransmitted to the sleeve 99 threaded thereon and through it to the capmember I02, thence through the thrustbearing H2, and collar III to thespring H0, and in turn to the flange I09, tubular member I06 and valveactuating arm 6i. Should an extraordinarily large piece of aggregate bein the path of either closing valve member 58, upon engagement therewiththe spring H0 will yield and be compressed so that movement of thethreaded rod 95 and the rock lever Bi through action of the cam section03 may continue while the movement of the tubular member I06, actuatingarm GI and valve plug 52 may be arrested, thereby obviating any dangerof damage to the various parts through strain imposed by the presence ofthe large piece of aggregate in the path of the closing valvemember.Obviously the force exv erted by the spring IIO may be varied byadjustplained to accommodate the valve restriction to different sizes ofaggregate, movement of the position of the pins 85 in the slot 62 callsfor a lengthening or shortening of the length of the connecting rodassembly 66. That is to say, if we assume the valve actuating arm, 6i tobe in the position shown in Figure l in which the valve is fully open,and the apparatus at rest, as it must be in order to change the settingof the valves, if the pin is moved outwardly m the slot 62, the arm 6|will be swung in a clockwise direction since the pin 05and connectingrod assembly 66 will swing about the pivot 91, as will be readilyunderstood, thus moving the valve from the com- 55 pletely open or zeroposition. In other words,' unless a change be made in the length of theconnecting rod assembly 86 the valve would then never reach completelyopen position and would impose partial restriction in the passage 42 atgo all times, which of course would be detrimental. In order tocompensate for this the lock nut IN is backed oif and the sleeve 99together with the cap I02 is rotated relative to the rod and tubularmember I06 in the proper direction to 55 cause the threaded engagementbetween the rod 95 and the extension I00 to produce an overalllengthening of the connecting rod assembly. In

' this manner the beginning of the valve stroke or zero point may alwaysbe maintained at the 7 point illustrated in Figure 1 and indicated bythe line A in Figure 3. which is the maximum open position of the valve,irrespective of the arcuate travel of the valve as determined by theposition of the pin 05 in the slot 62.

The actual operation of the pump is similar to the usual piston pumps,it being understood of course that upon the outward or suction stroke ofthe piston H in the working chamber I3 the inlet valve is opened throughits cam while the outlet valve is maintained in maximum restrictedposition through its cam. When the direction of travel of the pistonisreversed the inlet valve is moved to restricting position while theoutlet ivalve is moved to completely open position and the concretemixture which has been drawn into the working chamber I3 through theinlet valve upon the suction stroke is forced out through the passages35, 42 and 53 into the pipe or conduit 1:31. The partial restriction ofthe es by the members 54 and II of the valves during the time they arein restricted position causes the concrete mixture to stow at suchpoints and prevent reverse movement thereof, as will be readilyunderstood.

The cylinder I! may be provided with asuitable relief valve lit incommunication with the working chamber whereby excess pressure withinthe chamber may be relieved and damage pre- -'vented to the apparatusshould by any chance an outlet valve fail to open.

Pumps constructed in accordance with the above disclosure and theaccompanying drawings, having a single piston of 7" diameter, and apiston travel of 10". have under actual working concapable of handlingfrom 15 to 20 cubic yards of concrete per hour. They have workedcontinuously from 8 to 12 hours per day, and maybe worked continuouslyfor longer periods, without requiring attention other than an occasionalflushing out of the ends of the valve housings. They may be stopped, asat meal time for periods of 30 minutes or more, and when started upthereafter will immediately function .with maxi- -mum eillciency, andwithout any cleaning out.

They should of course be completely cleaned and flushed throughout atthe final completion of a pumping operation, or if shut down forconsiderable periods of time, as overnight.

As has been previously stated the inlet and outlet passages such as 88,ll, II and flare preferably of the same diameter as that of the workingchamber l3 and the passages such as 42, ll and SI of the valves arelikewise of the same diameter so that there are no restrictions anywherein the system when the valves are in open position at which the flow ofthe concrete might be impeded, thereby causing it to stow?; nor arethere any pockets forming dead spaces in which concrete is not at alltimes moving and in which it would harden and build up. In the pumpsabove referred to the inletand outlet and valve passages are all of 7"diameter, the same as that of the working chamber it, although a slightover-sizing of the pump's cylinder-diameter, gradually merged into itsoutlet extension II, and a slight reduction, very gradually made, of thediameter of the delivery passage 4! or adjacent p ping fl, beyond theoutlet valve It, may be used with some advantages by way of lower costof the correspondingly-smaller delivery piping and the decrease inlabor-cost of moving it around on the job,although with some resultantlimitation as to size of aggregates and dryness of mixtures to behandled, distances to which they are to be delivered, increased wear onthe equipment, etc,

While one form of the invention has been illustrated and described it isobvious that those skilled in the art may vary the details ofconstruction as m well a's the precise arrangement of parts withoutdeparting from the spirit of, the invention and therefore it isnotwished to be limited to the above disclosure except as may be requiredby the claims.

what is claimed is:

1. In a concrete pump having a pressure chamber, a-pressure memberworking therein, and a material passage communicating therewith, aseatless valve for controlling said e including a housing and anoscillatory valve plug having complete circumferential clearance in thezone of its ports between itself and said housing at all times throughwhich paste-flowable constituents of the mixture may find their way,-said plug having an aperture providing a pair of spaced elements atopposite sides thereof; said aperture being of a size and shape toprovide a stowage-avoiding continuation of said materiale when alinedtherewith; "and means for intermittently oscillating said valve plugbetween an open position, in which its aperture is in axial alinementwith the e to afford unrestricted communication with the pressurechamber, and a position in which said aperture is angularly disposedrelative to the passage and each of said spaced elements at leastpartially restricts said passage.

2. In aaconcrete pump, the combination with aworking chamber, a materialpassage communir eating therewith, and means in said chamber forimparting movement to the material, of a seatless valve for controllingsaid e, including a ported valve member having complete clearance in thezone of its ports between itself and its surrounding structure, throughwhich pasteflowable constituents of the mixture may find their way.

3. In a pump for plastic concrete mixtures con-:

taining a substantial proportion of coarse aggre- I i gates which giveto the mixture a strong tendency to stow at restrictions, said pumphaving a cylinder with a substantially full-diameter end-opening, apressure member working therein, a min ture outlet-passage ofstowage-avoiding sectional area and contour relative to that of thecylinder and communicating axially with the open end thereof; a seatlessvalve in said outlet-cincluding a ported housing member and a portedrocking plug member, these members providing. a valve-pway ofstowage-avoiding sectional area and contour relative to that of thecylinder, said valve members providing between them throughout the acneof their ports constantly open peripheral clearance of suitable depth topermit e therethrough of only the pasteilowable constituents of themixture; and means for moving said plug member to bring its passagewayinto and out of register with the posts of its housing in timed relationto the move- 10 ments of the pressure-member.

4. In a pump forplastic concrete mixtures'containing coarsev aggregatesand paste-flowable constituents, a horizontally disposed cylinder with afull-diameter end opening, a piston work "i ing in said cylinder,mixture outlet and inlet passages each of sectional area and contourapproximating that of the cylinder for respectively receiving mixturefrom and delivering mixture to said open end of said cylinder,respective valves for said outlet and inletpassages each including ahousing and a rocking plug valve member therein providing avalve-passageway of sectional area and contour also approximating thatof the cylinder, there being at all times free clearance between eachsaid housing and its valve-plug through which the paste-flowableconstituents only of the mixture may freely pass, and means for movingsaid valve-plugs to and from open position in appropriate timed relationto movements of said piston.

' 5. In a concrete pump for handling coarse aggregate concrete, having acylinder, an outlet passage connected therewith, and a piston in saidcylinder for forcing material through said passage, the combination of aseatless valve controlling said passage, including a rocking plugvalve-member and its housing, there being complete clearance in the zoneof said passage between said valve-member and housing through whichpaste-flowable constituents of the mixture may freely pass for avoidanceof lodgment and sticking; there also being clearance between the ends ofsaid valve member and the housing; packing between the housing and valvemember separating said passage-zone clearance from said end clearancesand tending constantly to prevent escape of said constituents from theformer into the latter; and openings through which a medium may beintroduced into said end clearances to prevent the hardening therein ofsuch said constituents as may find their way past said packing.

6. In a pump for plastic concrete mixtures embodying substantialproportions of coarse aggregates. said pump having a pressure chamber, apressure member working therein, and a mixture passage communicatingtherewith, a seatless valve for controlling said passage, including ahousing and an oscillatory valve member provided with an unobstructedpassageway therethrough having a cross sectional area and contourafiording a stowage-avoiding continuation of said mixture passage whenalined therewith, there being complete circumferential clearance at alltimes in the zone of the passage ports between said .valve member andhousing through I which paste-flowable constituents of the mixture mayfind their way; and means for moving said valve member to bring itspassageway into and out of register with said mixture'passage.

'7. In a pump for plastic concrete mixtures embodying substantialproportionsof coarse aggregate which giveto said mixtures a strongtendency to stow at restrictions, said pump having a pressure chamber, apressure member working therein, and a mixture passage communicatingtherewith, a seatless plug valve for controlling said passage, includinga plug, member having an unobstructed passageway therein, providing apair of spaced cut-off elements, said passageway being of substantiallythe same contour and of equal cross sectional area as said mixture passage, there being complete circumferential clearance at all timesbetween said plug and its enclosing structure in the zone of saidpassageway; and means for moving said valve member from an open positionin which its passageway is alined with said mixture passage forming asmooth contlnuatlon thereof, to a position in which each of saidelements at least partially restricts said passage.

8. In a pump for plastic concrete mixtures embodying substantialproportions of coarse aggregates, said pump having a w'o'rking chamber,a 5

pressure member working therein, and a mixture passage communicatingtherewith, a seatless valve, including a housing having a portcommunicating with said passage, and a movable valve member within saidhousing having a stow- 1 age-avoiding mixture passage and a cut offelemerit arranged to be moved at least partially across said port, therebeing complete clearance at all times between said valve member andhousing in the zone of said port through which paste- 15 flowableconstituents of the mixture may find igeir way; and means for movingsaid valve mem- 9. In a concrete pump having a pressure chamber. apressure member working therein, and material inlet and outlet passagescommunicating therewith, seatless valves for controlling said passagesincluding housings and oscillatory valve members therein, there being atall times free clearance between said housings and oscillatory valvemembers larger than the fine, paste-flowable constituents of theaggregates and through which such paste-flowable constituents mayfreepass without binding said oscillatory valve members to saidhousings.

10. In a pump for plastic concrete mixtures which embody substantialproportions of coarse aggregates which give to such mixtures a strongtendency to stow at restrictions, a horizontal working chamber; apressure member working therein; an inlet passage communicating withsaid chamber from above, said passage having a stowage-avoiding crosssectional area and contour relative to that of said chamber; ahorizontal outlet passage in axial alinement with said working chamber,of substantially the same cross sectional area and contour as saidchamber, forming a smooth continuation thereof; valve means forcontrolling said passages; and means for actuating said valve means intimed relation to the movements of said pressure member to open saidpassages alternately to said chamber, said valve means being arranged toprovide in open position an unobstructed communication passagesubstantialty as large in cross sectional area as said chamber.

11. In a pump for handling concrete includin large aggregates, a workingchamber'with an open end, a pressure member working therein, inlet andoutlet passages both communicating with said working chamber at its saidopen end; valves for controlling said passages, each valve including anoscillatory valve member having a passageway therein which in the openposition of the valve is aligned with its respective passage, saidpassages and valve passageways being of a substantially uniform diameterthroughout which is substantially equal to that of said working chamber,whereby the concrete mixture being pumped may pass into and out of saidwork- 55 ing chamber with a minimum of disturbance of the largeaggregates of its mass, and mechanical means for operating the valves intimed relation to the operation of said pressure-member.

12. In a pump for handling concrete mixtures having a strong tendency tostow upon restriction, a pressure chamber, a pressure member workingtherein, a mixture conduit communicating with saxlchamber which is ofstorage-avoiding cross-sectional area and contour relative to of whichits passage is partially misaligned with respect to said conduit wherebymixture in said valve passage is partially but not wholly cut frommixture in said conduit to cause the mixture therein to stow, all intimed relation to the working of said pressure member.

13. In a pump for plastic concrete mixtures containing substantialproportions of coarse aggregates, a working chamber perimetrally closedthroughout its length and having an axial end opening ofstowage-avoiding cross-sectional area and contour relative to that ofsaid chamber, a piston working in said chamber, an inlet passage and anoutlet passage for the mixture adapted to be alternately fully openedinto communication with said end opening of the working chamher, thecross-sectional area and contour of each of said passages relative tothat of the'working chamber being such as to avoid stowing of themixtures, and mechanically actuated valve means beyond said open end ofthe working chamber for valving the concrete mixture from said inletpassage to said working chamber and from said working chamber to saidoutlet passage alternately in timed relation with the movements of saidpiston.

14. In a pump for plastic concrete mixtures containing substantialproportions of coarse agregates giving the mixture strong tendency tostow, a substantially horizontal cylinder having a single opening in itsend which is of stowageavoiding cross-sectional area and contourrelative to that of the cylinder; 9. piston working in said cylinder formoving the concrete; an outlet passage and an inlet passage opening incommon to said cylinders end opening and thewalls of each whereofnowhere include substantially less or more sectional area for concreteconfinement than the sectional area of said end opening of the cylinder,whereby both unwanted stowing and dormancy of the mixture aresubstantially minimized, said outlet passage extending in axialalignment with the cylinder and said inlet passage extending upwardlyfrom said axis; and rocking-plug valve means operating in timed relationto said piston for fully opening and thereafter at least partiallyclosing said inlet and outlet passages alternately.

15. In ,a pump for plastic concrete mixtures containing substantialproportions of coarse aggregate giving the mixture strong tendency tostow, a cylinder having a single end opening of substantially thesectional area of the cylinder, a piston in said cylinder for moving theconcrete, two passages opening in commonto said cylinder opening and thewalls of each whereof nowhere include" substantially less sectional areathan that of said cylinder, and respective seatless rocking plug valvemeans for said passages operable in timed relation to said piston forfully opening and thereafterat least partially closing said passagesalternately, and each said valve having constantly open circumferentialclearance for passage of only the paste-flowable constituents of themixture.

16. A pump'for moving concrete that embodies substantial proportions ofcoarse aggregates,

having a piston; a horizontally disposed cylinder in which the pistonworks Having an end opening; a branched pipe structure for directing theconcrete into and out of the cylinder, having a horizontally disposedoutlet portion and an inlet 5 portion branched upwardly therefrom andmerging therewith for common communication of the branches with the endopening of the cylinder, said inlet branch having a smooth longitudinalcurve toward horizontality below its upper 10 circular inlet end tosubstantially the cylinders end opening, and the outlet branch having acircular opening at its delivery end approximately of cylinder diameter,the walls of each said portion being of substantially uniform cross-sec-15 tional curvature throughout and the merged portions thereof smoothlyconnecting with the respective bottom and top portions of the cylinderopening; and valving means for said inlet and outlet branchesrespectively, each openable 20 to the full cross-sectional area of itsrespective branch.

17. In a concrete pump having a pressure chamber and a pressure memberworking therein; a mixture inlet passage and a mixture outlet 25-passage communicating with said pressure chamber, each being of astowage-avoiding cross-sectional area and contour relative to that ofthe pressure chamber; a valve in each said passage movable fromnon-restricting position to posi- 30 tion at least partially restrictingsaidpassage; mixture-conveying piping connected to the outlet passageand of substantially the same sectional area and contour as the latterand therefore conducive to continuance of movement of appropriate timedrelation to the movements of 40- I the pressure member, to cause thevalve in the outlet passage to move to restricting position and theinlet valve to move to non-restricting position with an overlap of theirnearly-semi-open positions occurring during such period of inertia 45-movement of the mixture, thereby minimizing -return or back-slip of saidejected mixture through the outlet and inlet passages.

18. In a pump for plastic concrete mixtures containing substantialproportions of large ag- 50 gregates giving the mixture a strongtendency to stow, a pressure cylinder, a reciprocating piston thereinfor imparting motion to the mixture, a mixture outlet passage openingaxially to the end of said cylinder and of stowage-avoiding 55cross-sectional area and contour relative to that of said cylinder, arocking plug valve controlling the passage and having a. plug-opening ofthe full passage-area, and means for reciprocating said piston androcking said valve, between reso spective positions that fully open saidpassage and at least partially restrict it, in appropriate timedrelation; said means including, in, combination, a piston-drivingcrank-shaft; camming means receiving rotation from said shaft and 05having distinct cam-portions for respectively causing movements of saidvalve from each of its respective positions to the other thereof; arocker arm and valve-rocking connections between said arm and the valveplug, said arm 2,017,975 tively provide for prompt stowing of theaggregates and full freeing thereof from restraint, in closely timedrelation to the piston travel.

19. In a pump for plastic concrete mixtures concross sectional area andcontour relative to that of said cylinder coaxial with the cylinder andopening to its end; a rocking plug valve for said passage which in oneposition fully opens said passage and in another position at leastpartially restricts said passages to cause the concrete to stow; andmeans for actuating said piston and quickly and positively rocking saidvalve from each of its said positions to the other in appropriate timedrelation to the pressure stroke of the piston, comprising,-incombination, a piston driving crank shaft; a rocker arm provided with ahousing; connections between said rocker arm and valve to rock thelatter as the arm is moved; a two-section cam secured on said crankshaft and positioned within said housing; and a pair er arm within saidhousing, each engageable by one respective section of said cam andthrough movement thereof by the cam imparting. positive and rapid motionto said arm and valve in a corresponding direction only, all in'predetermined timed relation to the reciprocation of the piston.

20. A seatless valve forhandling plastic concrete mixtures of paste,fines and large aggregate, comprising a housing having a port ofsubstantially larger area than that of a gradingscreen opening throughwhich the largest aggregate will pass, and a movable valve member insaid housing controlling said port and having a passage which in oneposition fully opens the port, there being complete clearance at alltimes between said valve member and its housing in the ported zone ofthe latter through which the paste-fiowable constituents of the mixturemay freely pass.

21. A seatless valve for handling under pressure plastic concretemixtures that include cement-paste, fines, and large aggregates,comprising a housing having large opposed ports, and 'an oscillatoryplug valve-member in said housing for controlling said ports and havinga passageway through it of cross-sectional area adequate to fully opensaid ports; there being complete circumferential clearance at all timesbetween said plug and its housing in the zone of said ports throughwhich paste-fiowable constituents only of the mixture may freely passwithout sticking or binding the valve.

22. The steps in the method of transporting plastic concrete mixturesembody ng substantial portions of coarse aggregates which'give to themixture 9. strong tendency to stow, which comprise imparting motion byrespective pressure applications to successive confined portions ofapplications, moving respective sections of such stream out of alignmentwith the remainder thereof without entirely severing their connectiontherewith, and while preserving substantially their original contour,thereby producing respective stowings of the material, and respectivelybodily replacing the so-moved sections to restore continuity to thestream, thus relieving the respective stowing actions and permittingresumption of movement of the stream.

23. The steps in the method of transporting plastic concrete mixturesembodying substantial proportions of large aggregates which give to themixture a strong tendency to stow, which comprise delivering successiveconfined charges of the mixture for pressure application; applyingpressure successively to confined portions of said delivered mixture;combining by said pressure applications such successive portions into acontinuous confined stream; at predetermined times, and alternately,bodily moving sections of the material being delivered to the pressuremeansand sections of the material being moved beyond said pressuremeans, out of alignment with the respective portions of the mixture ofwhich they are immediate parts, at the same time preservingsubstantially the original contours of said sections, thereby producingstowing actions alternately in said parts where each saidout-ofalignment movement is respectively effected, and subsequently andalternately bodily restoring said respective so-moved sections intocontinuity with the'respective portions of the material of which theywere immediately a part, thereby relieving stowing action and permittingforward movement of the material, such out-of-line moveof sections ofmaterial being made in timed relation to the successive pressureapplications.

24. The method of transporting plastic concrete mixtures embodyingsubstantial propor- 40 tions of coarse aggregates which give to themixture a strong tendency to stow, which comprises, in alternate steps,delivering under suction successive charges of the material fromtransverse confinement that gives it definite cross-sectional area andcontour into transverse confinement that gives it substantially the'samecross-sectional area and contour, and thereafter imparting longitudinalmotion to successive portions of the material while under saidsecond-mentioned confinement through the application of pressureinitially and directly along the line of such motion to eject them pastthe point of the materials delivery to said second-mentionedconfinement; combining said pressure-ejected successive portions into acontinuous stream under transverse confinment of substantially the samecrosssectional area and contour aforesaid for transportation under suchconfinement to destination, thereby minimizing pressure-compelledrearrangement of the relative positions of the large aggregate pieces indelivery to and ejection from the second mentioned confinement; andalternately interrupting the movements of the confined material beingrespectively delivered to and ejected from said second mentionedconfinement in timed relation to the alternate applications of pressureand suction.

, JACOBUS C. KOOYMAN.

